Effect of crop weed competition on growth parameters of wheat crop
Plant height
Significantly highest plant height was recorded in monoculture among the crop establishment methods while lowest was recorded in wheat sown with
Avena and
Phalaris (Table 1). This might have happened due to weeds are growing vigorously and has more ability to achieve greater height, develop wide leaf area and horizontal branches when moisture and nutrients are not limiting which allow them to shade and suppress the growth of the main crop to a last level of yield reduction. These results were in collaboration with the findings of
Khan et al. (2007) and
Sinha et al., (2009).
Shoot length
Shoot length is one of the important functional traits which express morphological growth of the plant. Significantly highest shoot length was recorded in monoculture which might have happened due to the fact that shoot length of wheat undergoes significant reduction under mixed-culture combination with
Phalaris minor and
Avena sativa (Table 2). Further, it was also observed that weed had the more competitive ability and has comparatively better growth efficiency in shoot height than the crop. This might be due to the similarity between physiological and morphological traits of wheat and the weeds which resulted in similar capacity to utilize the natural resources. Similar findings were also reported by
Sinha et al., (2009) and
Singh et al., (2017).
Number of tillers
Number of tillers reflects the establishment of crop, canopy structure and also the yield to be obtained from the crop, so these are the direct indicators of vegetative growth progress of crops. Significantly highest number of tillers were recorded in monoculture. However, significantly the lowest number of tillers were recorded in wheat crop sown in association with
Phalaris minor and
Avena sativa indicating high degree of suppression up to 22.34 % is provided by the weeds (Table 3). The findings of the present experiment are in accordance with there of
Pisal and Sagarka, (2013) which specified that number of tillers of wheat crop undergo reduction in wheat-weed mixture plots than monoculture and it was also observed that
Avena fatua was found to be more dominating than
Phalaris minor in effective tillers of wheat crop.
Shoot weight ratio
Wheat crop sown with associated weeds on shoot weight ratio varies significantly. However, the significantly lowest difference was observed between monoculture and crop sown with associated weeds (Table 4). This is probably due to more capacity to accumulate nutrient, more photo synthesis and more dry matter uptake by weeds from the soil which provided more competitive regimes to that in turn struggling for nutrient utilization by wheat crop.
Effect of NPK and water Treatments
Plant height
A perusal of data presented in Table 5 revealed that significantly highest plant height was observed with full dose of NPK which indicated that with an increase in doses of NPK increase the corresponding parameter and decreased in water deficit conditions. These results are in accordance with findings of
Raghuwanshi et al., (2018). This might be because of the favourable environment of growth resulted in more cell division and cell elongation in the meristematic tissues of plants that leads to a significant increase in the plant height.
Shoot length
The data presented in Table 6 revealed that significantly highest shoot length was recorded with a full dose of NPK. This parameter increased with an external supply of the nutrient resources in the form of NPK fertilizers and water supply. These findings are inconsistent with
Yadav and Dhani (2017).
Number of tillers
Significantly highest number of tillers were observed with a full dose of NPK (Table 7). This might have happened due to fact that with increasing rates of fertilizer application, particularly nitrogen, may be attributed to enrichment of protoplasm content of the plant and acceleration of metabolic processes results in the maximum number of tillers. This may be due to increased cell division and meristematic activity resulted from supply of nutrients in the form of fertilizers. Similar findings were also observed by
Pandey et al., (2013).
Shoot weight ratio
Results showed that maximum shoot weight ratio was observed in HNPK followed by HNPK, control, HW and FW (Table 8). The same trend was reported by
Mohil and Jain, (2016) in which they found that there was a gradual increase in shoot biomass with an increase in the concentration of NPK at different plant growth stages. This may be due to an increase in fertilization which leads to a change in the allocation of biomass to plant parts causing an increase in accumulation of biomass in shoots
(Singh et al., 1991). On the other hand, it is seen that water treatments, HW has more shoot weight ratio than FW but both have less shoot weight ratio than control. According to the findings of
Shahi et al., (2015) in which they found that water stresses decreased the shoot biomass of wheat from control conditions, as less growth was seen under water deficit stress.
Effect of Interaction (Combinations × Treatments)
Plant height
The variables (combinations and treatments) showed significant effect on this corresponding parameter of wheat crop and its weeds (Fig 1). Competition between weeds and wheat crop for resources, particularly for nutrients and water might not have been severe in the early stage.
Shoot length
Maximum shoot length of wheat,
Avena and
Phalaris was observed in monoculture in FNPK while minimum in W+A+P combination in HW which showed 75.11% reduction (Fig 2). The variables (combinations and treatments) showed a significant effect on the shoot length of wheat and its weeds
Avena and
Phalaris has more shoot length. These can be related with the findings of
Bogale et al., (2011) in which they observed that light penetration was more pronounced in monoculture where more shoot growth than in wheat-
Avena mixture suggesting competitiveness of weed in the utilizations of given nutrients and water resources.
Number of tillers
Maximum growth number of tillers of wheat,
Avena and
Phalaris has been observed in monoculture in FNPK whereas minimum number of tillers of wheat in W+P in HW (Fig 3). Productive tillers reduction due to weed competition was started at 45 DAS for nutrients uptake from soil when NPK fertilizers were applied.
Shoot weight ratio
The results revealed that significantly maximum shoot weight ratio of wheat in monoculture and of
Phalaris observed in W+P combination in FNPK treatment whereas of
Avena in W+A+P combination in HNPK treatment while minimum of wheat in W+P in HNPK (Fig 4). These findings are in line with those reported by
Das and Yaduraju (1999) who also observed maximum dry weight in the weed free plots resulting in more accumulation of photosynthates and greater biomass under given fertilizers and water treatments.
